Installation

Fire Damaged Trusses

Question: 

I have been hired by an insurance company to determine the extent of damage to roof trusses exposed to fire. How much fire damage compromises the structural integrity of the truss?

Necessity Of Tags

Question: 

Are trusses required to have tags on all bearings that are not at the heel location? What about tags on webs requiring lateral reinforcement?

Scissors Truss Diagonal Bracing

Question: 

We are finding it difficult to design permanent diagonal bracing for scissors trusses. The truss is often only a few feet in depth, which does not provide adequate room for diagonal bracing. Has SBCA come up with recommendations for permanent bracing of scissors trusses?

Installing Valley Sets

Question: 

What are the requirements for installing “valley set” overlay roof trusses? I am interested in nailing and support conditions. Some engineers ask for the bottom chord of the valley truss to be ripped to match the roof pitch of the underlying trusses. Is this necessary?

Truss Blow Down

Question: 

If trusses blew down from insufficient temporary bracing and the contractor put them back up without the knowledge of the truss manufacturer and gave the truss manufacturer a letter stating that the trusses were okay, is that sufficient? Do you know of any truss manufacturer who would accept this?

Deflection Of Long Span Scissors Trusses

Question: 

I was wondering if you have any information or anecdotes relating to the deflection performance of long span scissors trusses? We recently sold a job with 70 ft. long scissors trusses. The customer is in the process of installing the trusses and doesn't like the deflections he is seeing. To make matters worse, the scissors trusses are framing into a valley set (which we provided) that is erected on 35 ft. Howe trusses. The Howe trusses are exhibiting very little deflection. Any ideas?

Truss Deflection Onto Non Load Bearing Walls

Question: 

I am installing a 40-foot scissor truss that is designed to deflect about ½ inch. I am concerned that the deflection will cause an interior partition wall to pick up some load from the truss and transfer it to the floor system. Should I double up the I-joists under this partition to pick up the extra load?

Jack Truss Connections To Girder

Question: 

In a hip roof application where jack trusses connect to a girder truss using pressure blocking (power blocking), what is the proper installation and the span that is acceptable before a hanger is required?

Vent Sizes

Question: 

I have mono trusses on either side of a firewall. I have the fire rating/wall material between them. Can I place a ridge vent above these two? Or should I use vents? How do I calculate the appropriate vent sizes and styles?

Old Fire Retardant Treated Lumber

Question: 

I have recently heard of a problem with fire-retardant-treated wood (FRTW) trusses that were manufactured and installed in 1965-1980. I was searching for more information, since my job involves the protection of property in our member school districts. I had heard that the trusses make of FRTW during that time period can or will become corrosive to the hardware and the trusses will fail.